A bone screw is provided comprising a longitudinal core member (10, 10') having a longitudinal axis (L) defining a longitudinal direction and having a surface, wherein a helical groove (15, 150, 15') is provided in a least a portion of the surface； and a helical thread body (20, 20') that is a separate part and that is provided in the groove (15, 150, 15')； wherein the groove (15, 150, 15') has a first width (wg) and the thread body (20, 20') has a second width (wt) and wherein the first width (wg) is greater than the second width (wt) such that the thread body (20, 20') can slide in the groove (15, 150, 15') in the longitudinal direction.本發明係為一種骨骼螺釘，包括：一縱向芯部構件(10,10')，具有一縱軸(L)界定一縱向，及具有一表面，其中一螺旋狀凹槽(15,150,15')係設置於該表面之至少一部分中；及一螺旋狀螺紋本體(20,20)，其係一分開件，及其係設置於凹槽(15,150,15')中；其中凹槽(15,150,15')具有一第一寬度(wg)，及螺紋本體(20,20')具有一第二寬度(wt)，及其中第一寬度(wg)係大於第二寬度(wt)，俾螺紋本體(20,20')可縱向地滑進凹槽(15,150,15')中。
